\begin{abstract}

We propose modifications to the Bitcoin mixing system \emph{Mixcoin} \cite{mixcoin} that keep the mapping of users' input addresses to output addresses hidden from the mixing server, all while maintaining the accountability guarantees provided by the \emph{Mixcoin} system. In order to acheive this, we make use of Chaum's signature blinding scheme \cite{chaum} as well as an append-only public log. The scheme is fully compatible with Bitcoin, forces mixes to be accountable, preservers user anonymity, is resilient to misbehaving users, and easily scales to many users.

\end{abstract}
